Research On Non-contact Vibration Measurement Technology Based On Optical Fiber Interferometer

Object vibration measurement methods mainly include mechanical measurement, electrical measurement and optical measurement. Because the advantages of high precision, wide range of frequency response and dynamic range, non-contact measurement, optical measurement techniques has been widely studied. By using optical interference technology*the vibration test technology based on optical fiber interferometer has a very high detection sensitivity and widely attention in the field of vibration measurement. Traditional interference signal detection is mainly implemented by the hardware. In recent years, virtual instrument technology based on computer platform can realize this function. Because of high performance, strong expansibility, short development time, etc, it has been widely applied.In this thesis, based on optical fiber Michelson interferometer, we use virtual instrument technology to achieve digital signal demodulation, and realize the accurate measurement of non-contact vibration signal. On the basis of the optical fiber Michelson interferometer, we use an optical fiber collimator as probe to realize optical signal coupling between optical fiber and the surface of vibration, so as to realize non-contact measurement. We choose the ARCTAN method PGC signal demodulation algorithm based on ARCTAN calculation which has been realized by the LabVIEW language and the phase output is expanded to the whole phase space. The effect of Carrier frequency and the filter bandwidth to the dynamic range of the system is analyzed, and an active low-frequency modulation by a large amplitude method is used to determine the amplitude of external modulated carrier.Experimental results show that the PGC signal demodulation method based on virtual instrument technology can well realize the interference signal demodulation. The system has realized the vibration signal measurement of1Hz to1KHZ, and it has good linear, high precision and good response to mutations signal. When the frequency of signal is1KHZ, the SNR of the system is40dB, harmonic suppression ratio is up to30dB, the resolution of the vibration measurement is better than2.47nm.